Gabriela Cabral and Peter Schlögelhofer at the Max F. Perutz Laboratories (MFPL) of the University of Vienna and the Medical University of Vienna have studied the process of meiosis in specific plant species, and found evidence that some of them carry out the inverse of the usual sequence of meiotic phases. They provide the first in-depth analysis of their meiotic behavior.
This was discovered to happen in Rhynchospora pubera (pictured above) and R.
tenuis, plants native to Brazil, which were initially what Cabral studied, but
then moved on to study C. elegans, a nematode worm. She found that all three organisms have
something in common: they all have the
same chromosome type present in them. Their holocentric chromosomes have the
property of, during somatic cell divisions, attaching spindle microtubules
along their entire length, unlike in humans where the microtubules attach to a
specific site known as the kinetochore.
This property means that holocentric chromosomes have
problems during meiosis that monocentric chromosomes do not face, so in order
to distribute the chromosomes correctly they have inversed the usual meiotic
sequence. The sister chromatids are separated during the first meiotic division.
Prior to the second meiotic division, the homologous non-sister chromatids are
associated with thin chromatin threads, and this allows for proper orientation
and disjunction during the second division.
I think that it is very interesting how some species of plants
have completely changed the steps of meiosis I and II, but yet come out with
the same result, if not better. I wonder if these plants have only recently
developed this process of inverse meiosis, or if this is a process much older
than what we think is “normal” meiosis.
Link to article: http://www.sciencedaily.com/releases/2014/10/141029124555.htm
No comments:
Post a Comment